Workers continue to dig through the rubble of Plaza Towers Elementary School after a tornado moved through Moore, Okla. / Sue Ogrocki, AP

by Rick Jervis , USA TODAY

by Rick Jervis , USA TODAY

MOORE, Okla. - Kelly Nichols ran up to the front door of Plaza Towers Elementary to retrieve her 9-year-old son, Ethan, and had to stop to catch her breath: the school's front glass faÃ§ade had been pulverized, the roof was gone, walls had been punched in, and a car lay flipped inside the main hallway.

The muscular tornado that mauled through town moments earlier had pummeled the school. Ethan was inside.

"That was the worst moment," Nichols, 36, said on Wednesday, as she picked through the ruins of her home, which is two blocks from the school. "I've never felt fear like that in my life."

Plaza Towers Elementary sat directly in the path of the tornado that ravaged Moore and parts of Oklahoma City on Monday. Unlike past tornadoes, this one burst into town just past 3 p.m., when students were still in class. School officials made the difficult, though oft-rehearsed, decision to keep students on campus.

That decision turned deadly at Plaza Towers. Seven of the 24 people killed by the tornado were students at the school, including at least four third-graders who huddled in the same building as Ethan, a second-grader, Nichols said. Briarwood Elementary, less than two miles west, was equally damaged by the storm but no students died there. Neither of the schools had safe rooms.

Moore Public Schools Superintendent Susan Pierce said earlier this week that the district launched its crisis plan as soon as officials learned of the impending severe weather.

"When our children are at our schools, they are in our care," Pierce said. "When it was time to shelter, we did just that."

School officials haven't released details of what happened inside Plaza Towers on Monday. But interviews with parents whose children attend there offer a glimpse into those terrifying moments when an EF5 tornado roared into their classrooms.

Kristopher Lawson, 33, had just gotten home from work when the TV stations started to warn of a large tornado forming in the area. He hopped in his car and sped across the street to Plaza Towers to get his son, Chandler, a second-grader, who was in the back building. A school official told him they were keeping the students at school but he was free to get him "at your own risk," Lawson said.

Lawson got Chandler from his classroom and told him to run to the car. They sped off to Lawson's father's home across town, which has a storm shelter.

The decision to get Chandler was an easy one, he said.

"I wanted him with me, no matter what," Lawson said. "I'd feel horrible if I'd left him in there."

Nichols was home when the TV stations showed a tornado touching down and headed her way. She had attended grade school at Plaza Towers, was head of its Parent Teacher Association and knew the routines school officials practiced for sheltering students on campus during storms. She decided to leave Ethan in school rather than get him.

"I figured the kids will be safe in school," she said. "I didn't think (the tornado) could do that to a school."

She jumped in her pickup truck and drove north, away from the path of the storm. When she returned, her neighborhood had been transformed into an unrecognizable landscape of flattened homes and the school was a clump of debris and rubble. As she ran to the school, its principal, Amy Simpson, ran out, screaming for help, Nichols said.